Among Diamond-Like Carbon (DLC), some hydrogenated amorphous carbon (a-C:H) coatings may exhibit superlow friction behavior (i.e. friction coefficient in the millirange) under Ultra-High Vacuum environment. Hydrogen content, environment and some mechanical properties have been identified as key-requirements to achieve such low coefficient of friction. Nevertheless, this exceptional friction regime may last only few hundreds of cycles depending on the film nature. It is believed that adhesive phenomena may account for such drastic friction increase. In order to better understand the tribological mechanisms governing the achievement and loss of superlow friction, comparison of the wear tracks at different stages of friction with pristine surfaces have been performed by Atomic Force Microscopy (AFM) in contact mode. While surface of a-C:H films appears smooth by conventional means of observation, AFM revealed a nanostructured surface with pads of about 10 nm height and 100 nm wide. The wear of these pads during sliding seems to be correlated with the loss of superlow friction. The relations between topography and superlubricity of such materials will thus be discussed.